Consider the question. In astronomy, Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun.

Answer this question based on the passage: what law describes how a planet orbits the sun?
 What is the step-by-step reasoning process to arrive at the answer: Kepler 's laws of planetary motion?
The relevant information is: In astronomy, Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun.